The management of many medical conditions requires the measurement and monitoring of a variety of analytes, e.g., glucose, in bodily fluids. Currently, the measurement of analytes in blood typically requires a venipuncture or finger puncture to obtain blood for sampling purposes. More recently, techniques for analyzing interstitial fluid components have been developed. Regardless of the bodily fluid tested or analytical method used, it is important that sufficient sample is collected in order to ensure adequate test results. In prior art methods, however, adequate sample collection is often a matter of trial and error.
It is therefore desirable to have a sampling and analyzing device giving a clear signal that adequate sample has been collected before the sampling device, e.g., a needle or other penetration device, is removed from the patient's body. It is also desirable that such a device be suitable for hospital bedside and home use.
Capillary and wicking fill devices are well-known as sampling devices and as sensing devices. However, one of the deficiencies of the prior art is that there is either no cue, or only a user-reliant visual cue, to indicate whether the device is fully filled.